1. Field of the Invention
This invention relates to a process for producing form-coke suitable for use in blast furnaces and other ore reduction furnaces, and more particularly, to an improved method of carbonizing green formcoke agglomerates.
2. Description of the Prior Art
Many processes are known for making agglomerates from carbonaceous solids and binders of different kinds. Briquetting presses, rotary retorts, balling drums and other equipment have been employed in these processes. The agglomerates so produced are then heated (calcined) to carbonize the agglomerates and make coke suitable for use in metallurgical operations. The term "formcoke" is used herein to describe agglomerates in the carbonized state. The term "green coke agglomerate" is used to designate the freshly formed agglomerate before heat is applied in the carbonization step or in a preliminary setting step to harden the agglomerate prior to the carbonization step.
The strength of the formcoke must be sufficient to sustain the "burden" of the ore reduction furnace. For use in the blast furnace, the strength of the formcoke should be very high to minimize formation of fine particles which decrease furnace burden permeability. Calcining of the agglomerates plays a critical role in producing formcoke of the required strength. However, one problem which has arisen with certain types of green coke agglomerates is they tend to be very delicate and any type of shearing forces whatsoever during any application of heat tends to cause deterioration of the agglomerate such as crumbling, loss of shape of the agglomerate and the like. Attempts to overcome this problem have utilized a setting step wherein the green coke agglomerate was heated for a time and temperature sufficient to prevent the deterioration of the agglomerate in the subsequent handling during carbonization. However, in order to prevent the pellets from sticking together during this heating step it was necessary to maintain very shallow beds such as two or three pellets (3 or 4) inches in depth and to heat for long periods of time such as three to five hours or longer.
Accordingly, an object of the present invention is to provide a method whereby green coke agglomerates can be calcined without significant deterioration and to increase the throughput of agglomerates in the setting step and to decrease the time in this step.